Quantifying human health risks from virginiamycin used in chickens.

Area of Science:

• Veterinary Medicine
• Public Health
• Microbiology

Background:

• Quinupristin-Dalfopristin (QD) treats vancomycin-resistant Enterococcus faecium (VREF) infections.
• Virginiamycin (VM) is used in farm animals, raising concerns about cross-resistance with QD.
• Traditional risk assessment models are data-limited.

Purpose of the Study:

• To develop a novel risk assessment model for VM use in chickens and its impact on QD effectiveness.
• To quantify potential human health risks associated with VM-driven QD resistance.
• To inform regulatory decisions regarding VM use.

Main Methods:

• Utilized a backward-chaining fault tree analysis approach, reversing traditional farm-to-fork modeling.
• Integrated human VREF case data with QD resistance rates and genogroup frequencies.
• Employed Monte Carlo simulation for a five-year risk projection.

Main Results:

• A ban on VM in Australia could reduce treatment failures by 0.35 x 10^-3 and mortalities by 5.8 x 10^-5.
• In the US, a VM ban could reduce treatment failures by 1.8 cases and mortalities by 0.29 cases over five years.
• The human health benefits of a VM ban are statistically small and decreasing.

Conclusions:

• The study presents a data-driven risk simulation model for VM/QD.
• The model suggests minimal human health benefits from banning VM in chickens.
• Results remain robust despite data uncertainties regarding resistance transfer.